Impregnated tip



March 29, 1955 o. s. PLANTINGA ET AL 2,705,009

IMPREGNATED TIP Filed Nov. 29, 1951 INVENTOR 0 /145? 6. 4A/V7/N44.

ARTA Of/rER ATTORNEY United States Patent IMPREGNATED TIP Oliver S. Plantinga, East Brunswick Township, Middlesex County, and Marta Deker, New Brunswick, N. J., assiguors to Johnson & Johnson, a corporation of New Jersey Application November 29, 1951, Serial No. 258,782

6 Claims. (Cl. 128-269) This invention relates to cotton swabs conmionly used for cleansing the nasal passages, particularly in children, for removing foreign bodies from the eyes, and for applying medicaments to the body.

Cotton tips adhesively secured to one or both ends of a stick are commonly formed by applying adhesive and then a wad of cotton to the end of the stick and thereafter, by suitable means, forming the cotton into the shape of a tip of reduced dimensions and symmetrical pleasing appearance. Using known means and procedures, difficulties have been encountered in producing a tip of compact but still absorbent structure and free from an excessive number of loose or unduly projecting fibers and from the tendency on the part of the cotton to become unraveled and/or disengaged from the end of the stick.

A particular object of the present invention is to produce a swab or applicator having a fibrous absorbent cotton tip free from the aforementioned disadvantages by means and methods which do not cause the tip to be irritating nor toxic in any way, not to become discolored or otherwise degraded upon aging or steam sterilization. It is a further object to produce an improved cotton swab without introducing to the tip, material which is in any way incompatible with medicaments which might be incorporated therein.

It has been found, according to the present invention, that fibrous absorbent cotton tips containing as impregnant any of certain water-soluble binding agents, i. e., those having long chain molecular structure, with recurring hydroxyl groups, possess markedly superior properties with respect to compactness of the tip consistent with good absorbency, freedom from excessively protruding fibers, and from tendency to unravel and/or come off the end of the stick. The peculiar combination of properties required of such an impregnant, namely, freedom from toxicity and irritation, compatibility with medicaments, and good aging characteristics, are also realized in the named bonding agents. The agents which are particularly suitable according to the present invention are the water-soluble methyl celluloses (which term as used herein includes substituted methyl cellulose, and sodium salt of carboxymethyl cellulose), the ethyl celluloses (including substituted ethyl cellulose, e. g., hydroxyethyl cellulose), and the polyvinyl alcohols.

Of the methyl celluloses, commercially available methyl cellulose, or hydroxymethyl cellulose, is advantageous for the purposes of the invention. Methyl cellulose having a degree of substitution in the approximate range 0.5 to 2.6 methyl groups per glucose residue will generally be found to have sufficient water solubility to produce a sizing solution which, when applied to the cotton tip, will effect the desired bonding of the fibers. Methyl cellulose having a degree of substitution in the approximate range 1.1 to 2.6 is particularly suitable. In the case of hydroxymethyl cellulose, the material may have a degree of substitution substantially above 2.6.

The ethyl celluloses are generally less soluble than the methyl celluloses, and accordingly, ranges of suitable degrees of substitution are somewhat narrower. Satisfactory material may be found in the approximate range 0.5 to 1.3 degree of substitution. Hydroxyethyl cellulose under comparable conditions is generally more soluble than the ethyl cellulose, and accordingly, the range of suitable degree of substitution is somewhat broader than for ethyl cellulose. Hydroxyethyl cellulose having desirably high solubility may be found in the approximate range 0.5 to 2.6 degree of substitution.

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The sodium salt of carboxymethyl cellulose (sodium cellulose glycollate) is another suitable bonding agent. The pH of the salt lies in the range 6-8, which is well within the U. S. P. specifications of a neutral material. The other desired properties, including inertness and compatibility, are also possessed by this impregnant. The degzrge of substitution should be in the range about 0.3 to

Polyvinyl alcohol is supplied commercially in a variety of types and by a variety of manufacturers. Any of these types which possess sufficiently high water solubility, as for example, those recommended for use in sizing solutions, etc., may be used for the purposes of the present invention. One type having a viscosity of 45 to 55 centipoises as determined by the Hoeppler falling ball method (determined in a 4 per cent aqueous solution at 20 C.), 98l00 per cent hydrolyzed (from vinyl acetate), and having a pH of from 6 to 8, may be used as a bonding agent in the present invention. This type polyvinyl alcohol is recemmended by the manufacturer as a sizing for yarn in 4 per cent aqeuous solution, or for paper in a 1 to 2.5 per cent aqueous solution. Another suitable type is that sold by the same manufacturer having viscosities of 35 to 45 by the Hoeppler method, 8689 per cent hydrolyzed, and having a pH in the range of 6 to 8. The latter polyvinyl alcohol was recommended by the manufacturer for sizing fine yarns.

The bonding agent of the present invention is incorporated in the tip in amount to produce to an appreciable extent the desired advantageous effects set forth above. Some bonding may be noted at extremely low proportions of bonding agent. However, it is preferred to incorporate at least about 0.05 per cent of the agent based in the weight of cotton in the tip. As the amount of the agent is increased above this value, the effectiveness of bonding increases correspondingly. The upper limit is determined primarily by the desire to avoid appreciable loss of absorbency and soft texture in the tip and further to carry out the operation with maximum economy. Accordingly, the amount of agent is generally maintained below about 0.5 per cent based on the weight of cotton in the tip. The preferred amount of agent is in the approximate range 0.15 to 0.20 per cent.

The concentration of the binding agent in the aqueous sizing solution is controlled within the limits of solubility of the particular agent employed (discussed above) concurrently with the pick-up of the sizing solution by the tip to effect the desired degree of incorporation of the agent into the tip. Further, the concentration should be sufiiciently low to provide sufficient fluidity of the sizing solution to permit the impregnant to become uniformly dispersed over the surface of the tip. Generally speaking, if pick-up of solution is to be low, higher concentration will be employed (consistent with good distribution of bonding agent), whereas if pick-up of solution is to be high, for example, of the order of 100 per cent, lower concentration may be utilized. A suitable range of concentrations is approximately 0.1 per cent as a practical minimum up to the saturation concentration of the particular bonding agent. Preferred concentrations which afford maximum ease and efficiency of operation lie in the approximate range 0.25 to 1 per cent.

Viscosity is a factor of some importance to consider in selecting a suitable bonding agent. The viscosity should be sufficiently low to permit application of sizing solution of a concentration which is suitable according to the foregoing description, i. e., provides sufficient incorporation of bonding agent and good distribution thereof, by the particular apparatus at hand. Solutions having viscosities below about 2,000 centipoises at 20 C. and having concentration in the ranges indicated above will generally be satisfactory for sizing cotton tips. Preferred viscosities are in the approximate range 2 to 100 centipoises.

The structure of the invention cotton swab is clearly illustrated in the attached drawing in which Fig. 1 is a perspective view of a cotton-tipped applicator and Fig. 2 is an enlarged view, partially in section, of the cottontipped end of the applicator.

Reference number indicates the applicator assembly, 11 the stick, and 12 the tip itself. Adhesive 15 secures tip 12 to stick 11. Bonding agent 16 is dispersed in tip 12 generally in somewhat higher concentration toward the surface of the tip than in the region adjacent to the stick 11.

A variety of methods may be employed for forming the cotton tip and impregnating same with invention bonding agents. The elements of the method include applying adhesive to the end of the applicator stick, bringing a wad of cotton into proximity with the end of the stick and then forming the cotton wad into desired neat and symmetrical shape as shown in the drawings. This forming operation may suitably be carried out by holding the stick on a stationary axis while rotating the tip with its end in contact with the periphcries of two forming rolls. The peripheries of said rolls are concave and of a shape to form a tip of the desired configuration. The bonding agent may be incorporated in the tip by applying aqueous size solution thereof directly to one or both said forming rolls, e. g., by wick means, from which rolls the solution is wiped by the tip which is being formed.

Although the drawing and parts of the specification illustrate the invention as applied to a cotton tip disposed on the end of an applicator stick, the invention also applies to tips formed on both ends of a stick commonly used, c. g., in cleansing the nasal passages, particularly in children.

Example 1 In forming cotton swabs according to this invention, methyl cellulose having a degree of substitution of 2.0, a viscosity of 100 centipoises in 2 per cent solution at 20 C., was dissolved in water to form a solution of 0.5 per cent concentration. This solution, which had a viscosity of 5.0 at 20 C., was placed in a storage vessel and allowed to run dropwise through a small tube to one of the forming rolls on a machine manufacturing cotton swabs. Over a period of five minutes operating time, 20 cc. of the methyl cellulose solution were used. The cotton swabs so made were packed in boxes and subjected to steam sterilization. The tips did not adhere to one another in the box before nor after sterilization. Fibers on the outside surface of the tips were well scaled down. The appearance of the tips was markedly superior to control samples made without methyl cellulose or other bonding agent. A box of bonded swabs was aged for one week at 140 F. After this period, the tips were found to be highly absorbent and had excellent color and appearance. The tips made by the above procedure contained about 0.2 per cent methyl cellulose by weight based on the cotton.

Example 2 A cotton swab manufactured on standard equipment and possessing a fuzzy appearance caused by loose and unduly projected fibers near the exterior surface of the tip was dipped into an aqueous solution of hydroxyethyl cellulose having a weight concentration of 0.4 per cent. The hydroxyethyl cellulose employed had a viscosity of about 13 centipoises at 20 C. and a degree of substitution of about 2.3. The treated swab was dried, examined, and found to be substantially free of loose fibers and more compact than similar unbonded cotton tips. The treated tip contained about 1 per cent hydroxyethyl cellulose based on the cotton.

The claims are:

l. A cotton tip adhesively secured to the end of a stick, said tip containing as irnpregnant a water-soluble binding agent having long chain molecular structure with free hydroxyl groups of the class consisting of a methyl cellulose, an ethyl cellulose, and a polyvinyl alcohol, in amount in the approximate range 0.05 to 0.50 part by weight per part of cotton in said tip.

2. A cotton tip adhesively secured to the end of a stick, said tip containing as impregnant a water-soluble binding agent having long chain molecular structure with hydroxyl groups, of the class consisting of a methyl cellulose, an ethyl cellulose, and a polyvinyl alcohol, in amount in the approximate range 0.15 to 0.20 part by weight per part of cotton in said tip.

3. A fibrous absorbent tip adhesively secured to the end of a stick, said tip containing as impregnant methyl cellulose, in amount in the approximate range 0.05 to 0.50 part by weight per part of fibers in said tip.

4. A cotton tip adhesively secured to the end of a stick, said tip containing as impregnant methyl cellulose, in amount in the approximate range 0.15 to 0.20 part by weight per part of cotton in said tip.

5. A fibrous absorbent tip secured to the end of a. stick, said tip containing as impregnant a water-soluble binding agent having long chain molecular structure with free hydroxyl groups of the class consisting of a methyl cellulose, an ethyl cellulose, and a polyvinyl alcohol, in amount in the approximate range 0.05 to 0.50 part by weight per part of fibers in said tip.

6. A cotton tip secured to the end of a stick, said tip containing as impregnant a water-soluble binding agent having long chain molecular structure with hydroxyl groups of the class consisting of a methyl cellulose, an ethyl cellulose, and a polyvinyl alcohol, in amount in the approximate range 0.15 to 0.20 part by weight per part of cotton in said tip.

References Cited in the file of this patent UNITED STATES PATENTS 2,006,539 Deford July 2, 1935 2,123,750 Schulz July 12, 1938 2,340,311 Donovan Feb. 1, 1944 2,430,648 Schonrock Nov. 11, 1947 2,440,141 Donovan Apr. 20, 1948 2,576,068 Ganz Nov. 20, 1951 

